This invention relates to underfloor electrical distribution systems for buildings, and more particularly to electrical trench assemblies having improved means for vertically adjusting the opposite sides thereof.
The use of electrical trench assemblies to provide an electrified floor structure in modern buildings is well known in the art. The trench assembly may be used in cooperation with metal cellular flooring or in reinforced concrete flooring wherein cooperation is not required with metal cellular flooring. In either floor construction, it is difficult to lay a concrete layer so that the top surface thereof is completely level throughout.
Consequently, trench assemblies have included adjustment means by which at least the cover plates are disposed flush with the upper surface of the concrete floor.
Heretofore, the required vertical adjustment has been accomplished in three ways. In one instance, adjustment means including vertical levelling screws are provided at each side of the trench whereby the cover plate may be adjusted to a limited degree relative to the sidewalls which are each of a one-piece construction, see U.S. Pat. 3,166,633 (Guzan, Jr., et al). In the second instance, each trench side is of a three-piece construction wherein two of the pieces are manually adjustable relative to a stationary third piece. The pieces of each side are held in adjusted relation by clamping screws, see U.S. Pat. 3,530,627 (Carter et al). In a third instance, each trench side is of a two-piece construction including at least an upper side rail supporting the cover plate and a stationary lower element, the side rail and lower element being connected by a vertically oriented leveling screw. Typical examples of this third instance are provided, for example, by U.S. Pat. Nos. 3,074,208 (Seidel), 3,084,480 (Fork), and 3,545,150 (Butler).
The above-identified vertical adjustment methods operate satisfactorally in the intended floor structure environments. However, in floor structures designed to require a fill of concrete or other material of one to one and one-half inch above the crests of the metal cellular units, the known trench assemblied cannot be used. The vertical adjustment arrangements exceed the one to one and one-half fill requirement.